1. Field of the Invention
The present invention relates to a printing roll used in a printing method, and more particularly, to a blanket which may be adhered to a printing roll.
2. Discussion of the Related Art
The process of making an LCD or semiconductor device typically involves depositing a plurality of layers and etching the coated layers. In particular, CVD (Chemical Vapor Deposition) and sputtering methods are used to deposit layers, while photolithographic methods are used to etch the coated layers.
When forming a plurality of layers, complexities associated with deposition and etching can account for reduced productivity. Therefore, efficient mass production of LCD or semiconductor devices requires more simplified deposition and etching processes.
Compared with photolithographic processes for patterning coated layers, patterning processes employing printing are simpler and easier to accomodate.
When forming a desired pattern by printing, a predetermined material is coated in a desired pattern on a printing roll. To form the desired pattern on a substrate, the material printed on the printing roll is re-printed on the surface of the substrate by rolling the printing roll on the substrate. Because of their simplicity, patterning methodologies involving printing lend themselves favorably to processes demanding more efficient mass production.
FIGS. 1A to 1C are cross sectional views depicting a printing method according to the related art. As shown in FIG. 1A, printing material 20 is coated on a printing plate 10 in a predetermined pattern. When a printing roll 30 is rolled on the coated printing plate 10, the printing material 20 is printed on a blanket 35 disposed on the printing roll 30 (FIG. 1B). Then, the printing roll 30 containing the printing material 20 is rolled on a substrate 40 to re-print the printing material 20 thereon. As a result, the printing material 20 is formed in a predetermined pattern on the substrate 40.
FIGS. 2A and 2B illustrate a process for fabricating a blanket according to the related art. First, a mold 50 having a concave part 55 in a predetermined shape is prepared (FIG. 2A). The concave part of the mold 50 is then filled with a resin material used to form the blanket (FIG. 2B). To fabricate the blanket 35, the pressure part 60 applies a predetermined pressure to the resin material in the mold 50.
It is difficult obtain an accurate pattern using such a blanket, however. This may be attributed to imperfections in the concave part 55 when forming the mold 50 and to reduced pressure uniformity when the pressure part 60 is lowered.
If the non-uniform blanket is used, a defect may arise when printing the printing material on the blanket. FIG. 3 illustrates how a defect may be generated when a imperfect blanket 35 is used according to the related art. If, for example, a portion 35a of the blanket 35 is protruding, a non-designated portion 20a of printing material may be inadvertently printed on the blanket 35, thereby producing an undesired pattern on a substrate thereafter.